Well It seems yet another TD5 Issue "caught" up with me.
Whilst fitting my VSR relay for the twin battery setup, I heard dripping
water coming from under the car, now I had literally pulled the car back
on the drive to open the garage , then drove the front into the garage and turned it off again
before opening the bonnet.

Upon looking underneath I saw what I had feared and that
was pink OAT coolant dripping, I had an idea where it was coming from and
upon removing the engine acoustic cover from the top, my assumption was
confirmed. Below you can see the bottom of the front face of the cooler is
wet, and the drip on the pipe below. The engine mount was also full of
coolant.

This had literally just happened, as I had checked the
water a day or so ago and the level was spot on, and after noticing this
leak, I ran the engine up to temp to see how bad it was, but to my
surprise it only leaked when the engine was off and cold.

Now if you took this car to a dealer, it is highly
likely they would replace the whole unit, which at a cost of £250 + labour
etc it would not be a nice bill to get, especially as its most likely just
a seal that has gone and caused the leak. So after a little "googling" I
found several references to it and it seems its more common than you
think.

Now I like to fix things rather than replace if
possible, obviously cost is a good reason to, but fixing a serviceable
item is far more satisfying in my opinion. So it was time to see what was
wrong.

The housing of the cooler simply has 2 plastic ends that
are held in by them awful "latching" spring clamps, now they are not easy
to do when access is good, let alone down by the cooler. You can if you
wish remove the cooler assy from the vehicle and fix it on the bench, but
I chose not to disturb the other end and fix it in situ. To remove the
clamp I simply used a flat bladed screw driver and tapped one side of the
clamp to "unclip" it.....

Below is the clamp, which I'm sure you have had "fun"
with this type before!!!

Now to "ease" removal of the end fitting, I left the
hose connected for now and used that to "carefully" wiggle and tug the end
cap out of the cooler.

The was very little coolant loss when the cap was
removed, you can see the "o" ring in place on the end cap.

Next was the hose on the end cap, it's held
by a simple spring hose clamp, I removed that and tied the hose back in a
vertical position to retain as much coolant as possible and to be honest
not a lot came out anyway. Below a view inside the cooler.....

Here below is the end cap, which it looks to me, that it
was designed to have 2 "o" rings in place, but in the picture above you
can see only the very bottom one would do anything due to the shape of the
cooler body, maybe Land Rover changed their mind during design, who knows?
but 2 "o" ring seals would have DEF been better.

You can clearly see the "o" ring is VERY flat in cross
section, and this is the obvious cause of the leaking end cap. After
measuring the end cap "o" ring seat, and reading some of the stuff on the
internet I was happy that the correct replacement seal would be BS225, and
because of the environment its in, "o" rings made from Viton rubber would
be the correct choice.

I ordered a "few" up (always good to have spares) a
couple of days before, and also bought some proper "o" ring lube from the
same place.

Here below you can see the new "o" ring in place on the
end cap, and the old "flat" one next to it !!

I applied a very small amount of "o" ring lube to fit
the new seal, and then a light smear around its edge to aid re-fitting the
cooler end cap and to try and avoid "snagging" the seal in the process.

The refit is the reverse of the removal, be CAREFUL when
fitting the end cap back in, and then its a "fight" with that blasted
clamp, what you use to refit that is up to you, But I normally use side
cutters and small needle nose pliers to do it. Its fiddly and not easy,
but be patient with it!!.

If you wish you could use standard jubilee clips, but
you have to make sure they are "narrow" ones so they don't interfere with
the "pegs" molded into the end cap. Once your successful with that,
reconnect the hose to the end cap, and then top up the coolant as
required.

Run the engine up to temp to check for leaks, and also
check it when the engine is COLD as well.